Many types of armchairs can be put into two positions--(1) that of an ordinary chair with arms, seat, and back normally in place for a comfortable sitting position and (2) a chaise longue intended to give the user complete support in a generally horizontal position with an attached headrest and legrest, which can be connected to the armchair frame.
Such convertible chairs have the inconvenience fo comprising a supporting structure of legs or feet forming the base, on which the chair rests when it is "closed" (normal position) or "open" (stretched out), while the added elements, such as the headrest and the legrest, are unused in the closed chair and brought into an effective position only when it is open. This implies either a considerable weight for the whole chair because of the fixed structure of the base, complicated mechanisms for the concealment or removal of the legrest, or means for the flexion of the various parts to allow for the stretched-out position.